Crystallographic Texture of MgO and its Effect on the Growth of BaTiO3 Thin Films by RF Sputtering

Abstract:

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In this work, MgO thin films were prepared by rf magnetron sputtering technique on two
different substrates of Si (100) wafers and amorphous glasses. The influence of different deposition
conditions such as substrate temperature, Ar pressure, film thicknesses on the crystal structure of
MgO thin films were studied. BaTiO3 ferroelectric thin films were subsequently deposited on the
MgO films. The XRD results showed that the orientation of MgO films was dependent greatly on the
substrate temperature. A highly (100) oriented MgO thin films were obtained at the temperature of
800°C. The crystallographic texture has been deteriorated rapidly as the argon pressure decreased to
1.0 Pa. It has been also found that the film thickness has a great influence on the film orientation. High
substrate temperature, high argon pressure and a certain thickness appear to be favorable for
formation of a good texture for the MgO films. The structure and microstructure of the BaTiO3 films
were various both with deposition conditions and with the crystallographic texture of the MgO. A
highly (001) oriented ferroelectric BTO film was obtained on the MgO films with an optimized
deposition conditions.

Abstract: A chemical solution deposition process for preparation of highly (100)-oriented
Ba(Zr0.05Ti0.95)O3 films was developed. The orientation degree of Ba(Zr0.05Ti0.95)O3 thin films
prepared by this process can reach up to 99.1%. The electrical properties of the (100)-oriented films
prepared by this process have been studied. The Ba(Zr0.05Ti0.95)O3 films with a thickness of about 270
nm show a dielectric constant of ∼740 and a loss tangent of ∼3%. The remanent polarization (2Pr) and
coercive field (2Ec) are 3.2 μC/cm2 and 34 kV/cm, respectively.

Abstract: Nd-doped bismuth titanate and random oriented Bi4-xNdxTi3O12 (BNT) thin films were
fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique. These samples had
polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well
developed rod-like grains with random orientation. The remanent polarization (Pr) and coercive field (Ec)
of the BNT film with x = 0.5 were above 19 μC/cm2 and 50 KV/cm, respectively. Nd doping into BIT
caused a shift of the Curie temperature (TC) of the BIT from 675°C to 660, 520, 410 and 256oC for the
films with x = 0.25, 0.5, 0.75 and 1.0, respectively. The experimental results indicated that Nd doping into
BIT result in a remarkable improvement in ferroelectric and dielectric properties.

Abstract: BaTiO3 films with thickness of ~1 2m were prepared by chemical solution deposition on
LaNiO3/Pt/TiOx/SiO2/Si substrate with a thin highly (100)-oriented and high crystallinity BaTiO3
thin film (~140 nm) as a buffer layer. The BaTiO3 films prepared by using a 0.5 mol/L solution have
high crystallinity and still show (100) preferred orientation. The electrical properties of the
(100)-oriented BaTiO3 films prepared by this process have been studied. A dielectric constant of
~910 and a loss tangent of ~3.5% (1 kHz) were obtained. The remanent polarization (2 Pr) and
coercive field (2 Ec) are 4.0 μC/cm2 and 35 kV/cm, respectively.

Abstract: Bi4Ti3O12 (BTO) and Bi3.25La0.75Ti3O12 (BLT) ferroelectric thin films were deposited on Pt/Si substrates by RF magnetron sputtering with Bi4Ti3O12 (BTO) and Bi3.25La0.75Ti3O12 (BLT) targets with 50-mm diameter and 5-mm thickness. The microstructure and ferroelectric properties of thin films were investigated. The grain growth behavior and ferroelectric properties such as remanent polarization were different in these two kinds of film, the effects of La doping in the BLT thin film were very obvious.

Abstract: BaTiO3 (BTO) thin films were grown on (100) SrTiO3 (STO) single crystal substrates using the RF-magnetron sputtering technique (RFMS) in both pure argon and mixed Ar/O2 (20% O2) atmosphere. A La0.5Sr0.5CoO3 (LSCO) layer was deposited as the bottom electrode by a 90° off-axis single-target RFMS. θ-2θ X-ray diffraction measurements showed that BTO thin films grown in both cases had a highly preferred c-axis orientation (001). From hysteresis measurements, it was confirmed that both films are ferroelectric. The ferroelectric polarizations 2Pr were 6.6 μC/cm2 and 27.1 μC/cm2, for the BTO films grown in pure argon and in mixed Ar/O2 atmosphere, respectively.